This patent deals generally with self righting devices and more specifically with an apparatus which can contain sensors and radiation generators such as radio transmitters or light sources and can always maintain the radiation in a preferred orientation relative to gravity regardless of the position of the outer container of the assembly.
Perhaps the most commonly known self-righting devices are the child""s toy usually referred to as the xe2x80x9croly-polyxe2x80x9d clown and the self-righting punching bag. The first is a small plastic toy with a heavily weighted round bottom and a top with a clown body. The second is very similar in construction but is usually inflated, about three feet tall, and made of soft vinyl. Both of these toys maintain their upright position, and return to it when tilted, because the weight in the rounded bottom always seeks the lowest position due to the force of gravity. In fact, sea buoys and boats use the same principle to maintain an upright position, but they are not on a solid surface. Even the round bottom toys depend to some extent upon a flat surface, so that they can not right themselves if, for example, they are forced into a corner or a rock is placed under them.
There is a need for such a self-righting motion with the use of modern. technology. Emergency radio transmitters, crash site locator beacons, intrusion detectors, global positioning systems, and military radiation decoys all receive or generate radiation signals, and all have a preferred orientation for their antennas or beams. Inventors have addressed this problem with at least two completely different techniques.
U.S. Pat. No. 5,406,287 to Pinkus discloses an air dropped infrared decoy that has a spherical casing with multiple infrared sources on its surface so that at least one emitter will always be aimed upward regardless of the position of the casing.
U.S. Statutory Invention Registration H1560 to Gill et al discloses a crash site locator radio beacon dropped by parachute that uses a weighted hemispherical bottom to vertically orient a rod antenna and strobe beacon. This design, as most weighted rounded bottom devices, requires a reasonably flat smooth surface to assure proper orientation.
However, in the real world, and except for the residential environment in which the children""s toys are used, flat smooth surfaces are not usually available, so that, for instance, if the Gill device were to land in a gully or on a rock, there is little likelihood that the antenna and strobe beacon would be properly oriented.
It would be very beneficial to have available a structure which would assure the proper orientation of antennas, light sources, and other radiation sources regardless of the actual positioning of the overall structure.
The present invention is a self-righting assembly which always maintains itself in a prescribed orientation relative to gravity regardless of the orientation of the structure within which it is mounted. It is particularly useful for communication systems such as light sources and antennas of radio frequency transmitters that must be specifically oriented relative to gravity for proper transmission, and it can be installed in a larger structure of any irregular shape.
The structure comprises two containers that are transparent to the radiation of the included transmitter and which form two concentric spheres. The concentric spheres are actually the outer surface of an inner container which contains the active components of the assembly, and the inner surface of the outer container. The spheres are separated by a fluid within the space between the spheres.
Since there must be an accommodation to the possible thermal expansion of the fluid, the simplest method is to leave a small amount of space between the spheres unfilled by the liquid. It is also possible to completely fill the liquid space and include a device such as a bellows within either the inner or outer container to accept any increased liquid volume.
A more subtle requirement for the liquid is that its specific gravity must be such that the inner container has an approximate neutral buoyancy within it, that is, the inner container will neither sink nor rise within the fluid. This assures that the inner sphere does not touch the spherical inner surface of the outer container. This neutral buoyancy is easiest to accomplish by adjusting the weight of the contents of the inner container after an appropriate fluid is selected. The fluid must also be transparent to the transmitter""s radiation, so that, for instance, for a radio transmitter it must be a dielectric fluid. An antenna or another energy radiator and sensors and associated electronic circuitry are all enclosed within the inner container, which is weighted to always rotate and rest in a prescribed orientation relative to gravity, with a its heaviest segment down.
It should be noted that, although the terms xe2x80x9cinner spherexe2x80x9d and xe2x80x9couter spherexe2x80x9d are used throughout this specification, they refer to only the outer surface of the inner container and to inner surface of the outer container which are the only surfaces that actually need to be spherical to accommodate the rotation of the inner container. Although also shown as spherical surfaces for convenience and because such a configuration is easier to manufacture, the outside surface of the outer container and the inner volume of the inner container have no restriction on their shapes.
The assembly of the invention can therefore be dropped or thrown, and regardless of how it lands, the inner sphere will always take the same position because there is nothing to interfere with its rotation. The antenna or radiation source and also the internal sensors will always be oriented in the same position relative to gravity. Therefore, an upward directed antenna or radiation source will always be capable of vertical transmission. Furthermore, any included sensors will also be oriented as desired. For example, light detectors can always be oriented at an appropriate angle to the horizontal, and other sensors, such as vibration or magnetic sensors can be oriented horizontally if that is the desirable orientation in order to be most sensitive to ground activity.
The self-righting structure is particularly useful as a trespassing detector. For such applications the invention can be deployed in disguised form, for example, by being painted to blend in with its surroundings or by being encased in plastic artificial stone. To further reduce the probability of detection, a radio transmitter within a unit can be designed to transmit extremely short transmission bursts or to transmit only when an included sensor receives a signal. Furthermore, a global positioning system, and its receiving antenna can also be included in the assembly so that the unit can also transmit its own exact location.
The invention can thereby be used as a remote intrusion detector which is itself virtually undetectable.